1. Field of the Invention
The present invention relates to an improvement of thermosensitive fluidized fan coupling device for controlling rotations of an engine cooling fan generally in automobiles, thereby feeding a blast according to a running state to an engine all the time.
2. Description of the Prior Art
As exemplified in FIG. 5, a prior art fan coupling device of this kind comprises partitioning the interior of a sealed housing consisting of a cover (23') and a case (23") into an oil reservoir (25) and a torque transfer chamber (26) in which a driving disk (22) is installed by a divider (24) having an outflow regulating hole (24'), providing a circulation passage (27) ranging to a pumping function part by a dam (28) which is through from the torque transfer chamber (26) side to the oil reservoir (25) side, providing further an outlet (27") side on a nose opening of an almost semicircular groove (29) ranging to the circulation passage (27) provided around an inner peripheral wall surface of the oil reservoir (25) with a dissepiment held thereon so as to position at least one of an inlet (27') on the circulation passage side and the outlet (27") on an oil level present within the oil reservoir (25) regardless of the state in rotation or stopping.
However, while intended satisfactorily for preventing oil in the reservoir from accumulating in the torque transfer chamber through natural counterflow from the passage to the torque transfer chamber (26) side during a stop with the circulation passage (27) side coming below the oil level within the oil reservoir (25), preventing an abnormal fan noise from arising through checking a sudden rise of the fan rotation immediately after an engine, start-up, and for effecting a warm-up in cold season, the prior art fan coupling device has a problem inherent still therein such that the oil in the reservoir flows out of the regulating hold (24') naturally to accumulate much to the torque transfer chamber (26) side during shutdown of the engine with the overflow regulating hole side coming under the oil level of the oil reservoir (25) under the state of valve member opening the outflow regulating hole (24') of the divider (24) in a high-temperature operating state. Accordingly, after the engine is restarted, a rotational frequency of a driven side fan becomes high, as shown in formance curve B of FIG. 6, with the lapse of time, thus causing an accompanying rotation.